It is known (see German Auslegeschrift - Printed Application No. 1,124,021) to contact two counterflowing liquid phases in columns which contain perforated plates and in which one liquid phase is distributed by means of holes and the other liquid phase flows across the plates and from one plate to another along a zig-zag path.
There are also columns (see U.S. Pat. Nos. 2,609,276 and 2,610,108) which contain perforated plates and in which both liquid phases flow through holes. This system uses stepped plates, in which a portion formed with the holes for the heavy liquid phase is disposed below and a portion formed with the holes for the light liquid phase is disposed above the remaining portion of the plate.
The light and heavy liquid phases can flow through holes in inclined rather than stepped plates (see German Auslegeschrift - Printed Application No. 1,263,695) and is caused to flow from one side to a diametrical line and back rather than from one side to the other (see U.S. Pat. No. 3,632,315 and German Gebrauchsmuster - Utility Model No. 71 42 672).
It is also known to cause the liquids to flow from the periphery to the center and back to the periphery (see German Auslegeschrift - Printed Application No. 1,263,696).
It has also been proposed to provide mixer-separator extractors having a separating chamber which is filled with stainless-steel turnings to accelerate the coalescence (see German Pat. No. 1,442,444).
The throughputs which can be achieved with these processes and associated apparatus for contacting two liquids are not satisfactory, particularly with systems of two liquid phases having low surface tensions.